1. Field of the Invention
The present invention relates to a power transmission and a camera provided with the power transmission.
2. Description of Related Art
It is known that an imaging lens barrel of a camera includes a drive mechanism adapted to drive a lens frame for holding part of the lenses in an optical axis direction by using a motor shaft having a feed screw formed on the outer peripheral surface thereof and a notched nut engaged with the motor shaft (for example, refer to Japanese Patent No. 2890689).
The abovementioned drive mechanism has a release function that releases the engagement with the feed screw by the opening of the notched nut when an excessive force is applied, in order to protect the power transmission in the event of a malfunction in control.
However, in cases where the abovementioned drive mechanism is used in a camera or the like, the abovementioned release function may operate to release the engagement of the notched nut by the shock exerted when it is put on, for example, a table (especially, by inertial force to the optical axis direction).